The diagnosis of a bacterial disease is only the first step in its treatment and cure. Due to the existence of drug-resistant forms of many types of bacterial diseases, it is sometimes necessary to perform further tests in order to determine which antibiotic, among all of those known to be effective against the disease in question, will be effective for the particular patient and bacterium involved. Typically, these additional tests are carried out using culture methods. The various antibiotic agents are individually cultured with a patient sample, and the antibiotic which most effectively kills the bacteria is then elected for use in treating the patient.
While culture methods are useful in determining which antibiotic will be effective, they are very time-consuming, requiring as much as twelve weeks to determine antibiotic susceptibility. The resulting delay in beginning treatment can allow the disease to progress further, sometimes to the point where the patient dies. Recently, a new method has been developed which reduces the time necessary to determine antibiotic susceptibility to as little as two days. This method, which is disclosed in U.S. Pat. No. 4,861,709 to Ulitzur et al incorporated herein by reference, uses a specific bacteriophage which has the ability to infect the disease-causing bacteria. The phage causes the infected bacteria to produce an enzyme known as Luciferase. Luciferase is a well-known enzyme which, when combined with the substrate Luciferin, causes the substrate to emit light. In a phage-based test for antibiotic susceptibility, a patient sample is cultured individually with each antibiotic for a day or two. The phage is then added to the sample and incubated for a few hours, after which the Luciferin substrate is added. The sample is then observed for the presence of luminescence. If luminescence is present, the bacteria are still alive and the antibiotic with which they were initially cultured was not effective against them. If there is no observed luminescence, the bacteria are dead and the antibiotic with which they were initially cultured was effective against them.
Because phage-based antibiotic susceptibility tests are performed on patient samples containing live bacteria, they are dangerous to handle and special precautions must be observed. The addition of phage and Luciferin to the sample, and transfers of the sample between different containers, must be carried out in isolation from the general laboratory environment. These requirements have kept the phage-based antibiotic susceptibility testing method from wide acceptance. Presently, it is not possible to add the phage, and subsequently the Luciferin substrate, to the patient sample without opening the culture plate or test tube in which the sample is contained.
It is therefore an object of the present invention to provide an apparatus which contains all of the elements necessary for carrying out phage-based antibiotic susceptibility testing.
It is another object of the invention to provide an apparatus which can be used to sequentially add phage and Luciferin, at different times, to a patient sample or antibiotic culture while remaining sealed.
It is a further object of the invention to provide an apparatus which will allow gas transfer with the ambient environment while remaining sealed to bacteria.
It is a still further object of the invention to provide an apparatus which will permit instrumented detection of luminescence while sealed.
It is a still further object of the invention to provide an apparatus or device which can be used to sequentially add phage and Luciferin, at different times, to multiple patient samples or antibiotic cultures while remaining sealed.
It is yet another object of the invention to provide a method for carrying out phage-based antibiotic susceptibility tests, and other types of biological and non-biological processes, on liquid samples while the samples are contained in sealed sample wells.